Lock



FIG. 1 is a perspective view of a lock, showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a side view thereof;

FIG. 5 is another side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines in the figures are for environmental purposes only and form no part of the claimed design. 

CLAIM The ornamental design for a lock, as shown and described. 